Device for palletizing parcels

ABSTRACT

A device is provided for palletizing parcels, preferably stacks of tubular sections or flat lying sacks. Said device comprises a lifting frame, which can be raised and lowered in a stand and which is provided with a roller track, in order to slide the pallets on and off. Said device also comprises a conveyor, which supplies the parcels to be stacked and from which a controlled accepting unit accepts the supplied parcels and deposits them on a pallet, provided on the roller track. To align the pallets accurately in relation to the accepting gripper, there are stops or clamping strips that can be moved in opposing directions in the lifting frame above the conveying plane of the roller track. Said stops or clamping strips act on the opposing sides or comers of the pallet and fix them in a position, in which the accepting unit deposits the parcels with positioning accuracy, according to the predetermined pattern, on the pallet.

[0001] The invention relates to a device for palletizing parcels, preferably stacks of tubular sections or flat lying sacks. Said device comprises a lifting frame, which can be raised and lowered in a stand and which is provided with a guide, slide or transport track, preferably a roller track, in order to slide the pallets on and off. Said device also comprises a conveyor, which supplies the parcels to be stacked and from which a controlled transfer unit takes the supplied parcels and deposits them on a pallet, provided on the guide, slide or transport track.

[0002] For example, in the manufacture of sacks tubular sections, which are processed by molding the bottoms to the sacks, must usually be put into intermediate storage, because the tube drawing machines, producing the tubular sections, work at a significantly higher speed than the systems, processing the tubular sections into sacks. Such an intermediate storage is usually achieved by stacking the tubular sections into stacks, containing a predetermined number of items, and then depositing the stacks on manipulatable pallets. Furthermore, the manufactured sacks must usually also be stacked and the stacks must be deposited on pallets, in order to store or transport them.

[0003] In the known class of devices for palletizing, as described in the introductory part of the specification, there is the problem that the pallets, which receive the parcels and on which the parcels are deposited in multiple layers with straight edges, according to a specified pattern in accordance with the programmed control unit of the transfer gripper, are not aligned accurately in relation to the transfer gripper, so that the parcels are stacked into stacks that are offset or skewed on the pallet. This state can lead to problems during the conveying and storage sequence, because the stacks project beyond the side edges of the pallet.

[0004] Therefore, the object of the invention is to provide a device of the aforementioned class that guarantees that the pallets are always accurately aligned relative to the transfer gripper, so that it deposits the parcels to be palletized with positioning accuracy in several layers on the pallet.

[0005] The invention solves this problem associated with a device of the aforementioned class in that above the conveying plane of the guide, slide or transport track there are stops or clamping elements that can be moved in the opposing direction in the lifting frame and which act on the opposing sides or corners of the pallet and fix them in a position, in which the transfer unit deposits the parcels with positioning accuracy, according to the predetermined pattern, on the pallet.

[0006] In the device, according to the invention, the stops or the clamping elements, which can be moved in opposing directions, align the pallet in a predetermined position on the lifting frame and fix it in this position, whereby the stops can also act like clamping elements on the sides of the pallets with slight pressure and thus clamp the pallets in position. However, clamping is not necessary, since the stops can move the pallet into its correct position and hold it there even without the clamping effect. To prevent that the stops or clamping elements, which act on the opposing sides of the pallet, prevent the pallet from being moved into the aligned end position, the clamping forces of the stops or the clamping strips can be coordinated in such a manner that a pair of stops or clamping elements act only with less force on the pallet and the two other stops and clamping elements can shift the pallet into the aligned end position due to their greater force. When the pallet is accurately aligned on the lifting frame by means of the stops or clamping elements, the transfer gripper, which can be controlled by a computer, can deposit the parcels in layers, according to a predetermined pattern, in such a manner on the pallet that the palletized stacks exhibit straight edges and do not project beyond the pallets.

[0007] A further development of the invention provides that on both sides of the lifting frame are mounted four chain wheels around axles, running at right angles to the slide on and slide off direction of the pallets, so as to be mirror images in relation to the transversal central plane of the lifting frame. Two continuous chains run on each side of the chain wheels. Clamping or alignment strips are fastened to the opposing chains at right angles to the conveying direction. The chains are provided in such a manner with drives that they traverse the alignment strips in opposing directions. The alignment strips are coordinated in such a manner that in their joined position they fix the pallet to be loaded between them in a position, in which it is in alignment with the accepting gripper in the conveying direction. The drives of the chains are only so strong that they come to a standstill, when the pallet is moved by the alignment strips into a position, in which they rest on the front and rear side of the pallet.

[0008] To guarantee that the clamping or alignment strips will move synchronously, the shafts of the inside chain wheels can be coupled together by means of gearwheels.

[0009] Preferably a pressure medium piston cylinder unit acts as the drive on a chain.

[0010] To align also the pallet, slid on the lifting frame, at right angles to the conveying direction, a further development of the invention provides that on both sides of the lifting frame are mounted chain wheels around axles, pointing in the conveying direction. Two continuous chains run over said chain wheels; and the sliders or clamping strips, which run parallel to each other over holders, are fastened to the upper strands and the lower strands of the chains. Said sliders or clamping strips can be moved in opposite directions by driving the chains synchronously. Even this drive is formed only so strong that it comes to a standstill when the sliders or the clamping strips rest on both sides of the pallet.

[0011] Expediently the sliders are guided by guide elements, for example sleeves, on a traverse that runs at right angles to said sleeves.

[0012] To drive the chains, there is a pressure medium piston cylinder unit, whose piston rod is fastened to a slider and whose cylinder is fastened to the lifting frame. Expediently the pressure medium cylinder unit comprises pneumatic cylinders.

[0013] Preferably the lifting frame is provided with driven rollers so that the pallets can be accepted by the lifting frame by suitably controlling the drive.

[0014] One embodiment of the invention is explained in detail below with reference to the drawings.

[0015]FIG. 1 is a schematic drawing of a side view of the device for palletizing parcels.

[0016]FIG. 2a is a top view of the lifting frame of the device, according to claim 1, with which the alignment strips, aligning the parcels in the conveying direction, are described.

[0017]FIG. 2b is a top view of FIG. 2a, with which the sliders, aligning the parcels at right angles to the conveying direction, are described.

[0018]FIG. 3 is a side view of the alignment strips, aligning the parcels in the conveying direction, with related drives in a position, in which the parcels can be slid onto the lifting frame.

[0019]FIG. 4 is a view, corresponding to that in FIG. 3, in which the alignment strips are moved in the direction of their aligned position.

[0020]FIG. 5 is a side view of the sliders, aligning the parcels at right angles to the conveying direction, along the cutline V-V in FIG. 2b.

[0021]FIG. 6 is a view, corresponding to that in FIG. 5, along the line VI-VI in FIG. 2b; and

[0022]FIG. 7 is a view, corresponding to that in FIGS. 5 and 6, along the line VII-VII in FIG. 2b.

[0023] The device for palletizing parcels comprises a frame-shaped stand 1, in which a lifting frame 2 can be raised and lowered. To raise the lifting frame 2, it is fastened to continuous belts 3 or chains on the opposing sides. Said belts or chains run over belt pulleys 4 or chain wheels, which are mounted in the upper and lower area of the stand. The upper belt pulleys 4, which are preferably provided in pairs and lie opposite each other, are connected together by means of a synchronizing shaft 5, which is driven by a controlled motor 6. Mounted on the lifting frame 2 is a frame 7, in which are mounted rollers 8 of a roller track and which is also provided with alignment strips and sliders to slide and fix the pallets in an aligned position, as will be explained in detail below.

[0024] In the bottom position (not illustrated) of the lifting frame 2, empty pallets 10 are slid onto the rollers 8 of the frame 7 by hand or by means of a driven conveyor 60, after the pallet 10, which is located on the roller track and loaded with parcels 11, has been transported away or slid off. Then the pallet 10, slid onto the roller track 7, 8, is put into the correct position on said roller track by means of alignment strips and sliders; and then the roller track is moved in the upward direction by means of the lifting frame 8; and in particular into a position just below the transfer and positioning gripper 12, which then deposits the supplied parcels 13 on the pallet 10, according to a pattern, programmed into the control unit of the transfer gripper 12. The transfer gripper 12 exhibits a conventional design and can also be moved and additionally rotated not only in the longitudinal but also in the cross direction by means of a drive (not illustrated) in the guides of the stand 1.

[0025] The parcels 13, to be palletized, are supplied by means of a feed conveyor 14 in the upper region of the stand 1 and raised by means of a lifting table 15 in the end region of the feed conveyor 14, after said parcels have been aligned correctly in their transfer position in front of a stop 16. To accept individual parcels 13, the transfer gripper moves over the lifting table 15 so that said gripper takes from said table the next parcel 13 to be stacked. After depositing the parcel 13 in a layer, the lifting frame 2 is lowered by the height of the layer so that the transfer gripper 13 can deposit the next layer on the last one, thus stacking with a predetermined number of layers.

[0026] To align the pallets correctly on the frame 7 or the roller track 8, the pallets have alignment strips and sliders, which fix and slide the pallets into their correct position, as is also described in detail below.

[0027] As evident from FIG. 2, the frame with the rollers 8 comprises lateral struts 18, which are connected together, by means of the axles 19 of the rollers 8 and a traverse 20, to form the frame 7. On the ends of the struts 18 the chain wheels 22 are mounted on journals 21, which point in the outward direction. On both sides of the transversal central plane of the frame 7, in which the central roller 8 is mounted, chain wheels 26 are mounted at equal intervals on the shafts 24, 25 on the outside of the struts 18. Continuous chains 27, 28 run over the chain wheels 22 and 26. The shafts 24, 25 are connected together by means of mating gearwheels 29 outside the upper frame 18. Thus, the gearwheels 29 guarantee a synchronous run of the chains 27, 28 and in particular in the opposing direction. Alignment strips 31, 32 are fastened by means of holding elements to the chains 27, 28 at equal intervals from the central plane, which is formed by the axis of the central roller 8. The piston rod 34 of a pneumatic cylinder 36 acts over a connecting piece 35 on the bottom chain 28, so that the chains 27, 28 can be driven by means of a suitably actuated pneumatic cylinder 36 in the same, but opposite direction.

[0028] The ends of the rollers 8 are provided with chain wheels 37, over which run the drive chains that are driven by a controlled motor 38.

[0029]FIG. 3 depicts the alignment strips 31, 32 in a position, in which they are moved under the conveying plane of the rollers so that new pallets can be slid onto the roller track without any impediment, and filled pallets can be slid from it.

[0030]FIG. 4 depicts the alignment strips 31, 32 in a position just above the conveying plane of the roller track, in which they join and approach a pallet, located on the roller track, and align said pallet and fasten said pallet between themselves.

[0031] As evident from FIG. 2b, forked bearing legs 40 are fastened to the struts 18 on their inside. Between the forked bearing legs deflecting rollers or chain wheels 41 can be freely rotated. Over the rollers or the chain wheels 41 run continuous belts or chains 42. A strip shaped slider 44 is fastened parallel to the struts 18 by means of corresponding holding elements at the upper strands of the continuous traction means 42. A strip shaped slider 46 is also fastened parallel to the struts 18 by means of holders 45 at the lower strands of the continuous traction means 42. The two parallel strip shaped sliders 44, 46 lie in a common plane above the conveying plane of the rollers 8. The sliders 44, 46 are fastened to sleeves 47, 48, which stand at right angles to said sliders and which can be slid longitudinally on the traverse 20. The piston rod 50 of a pneumatic cylinder 51 is hinged to the slider 46. The pneumatic cylinder 51 is fastened in the frame 7.

[0032] The sliders 44, 46 are fastened to the upper and lower strands of the continuous traction means 42 in such a manner in relation to each other that they meet in the longitudinal central plane of the pallet to be aligned on the roller track. By suitably actuating the pneumatic cylinder 51, the sliders 44, 46 can be closed and opened like pliers.

[0033] The pneumatic cylinders 36, 51 are controlled by the machine control unit.

[0034] On the frame 7, bearing the rollers 8 and moved into its lower position, the pallets 10 are supplied over a roller track 60. The loaded pallets 10 are carried away over a roller track 61. When the frame 7 has reached its lowest position, it covers a reference point initiator, which permits the roller track to be started in order to carry away the loaded pallet and to supply the empty pallet. Then the empty pallet, slid or conveyed on the roller track 8, is aligned on said track by means of the alignment rails 31, 32 and the sliders 44, 46. Then the roller track with the empty pallet is moved by means of the machine control unit up to and just below the transfer gripper 12. 

1. Device for palletizing parcels (13), preferably stacks of tubular sections or flat lying sacks, said device comprising a lifting frame (2), which can be raised and lowered in a stand and which is provided with a guide, slide or transport track, preferably a roller track (7), in order to slide the pallets (10) on and off, and comprising a conveyor (14), which supplies the parcels (13) to be stacked and from which a controlled accepting unit (12) takes the supplied parcels and deposits them on a pallet (10), provided on the guide, slide or transport track (7), characterized in that above the conveying plane of the guide, slide or transport track there are stops or clamping elements (31, 32, 44, 46) that can be moved in the opposing direction in the lifting frame (2, 7) and which act on the opposing sides or corners of the pallet (10) and fix them in a position, in which the transfer unit (12) deposits the parcels with positioning accuracy, according to the predetermined pattern, on the pallet.
 2. Device, as claimed in claim 1 , characterized in that on both sides of the lifting frame (7) are mounted four chain wheels (22), over each side of which run two continuous chains (27, 28), said chain wheels being mounted around axles (21), running at right angles to the slide on and slide off direction of the pallets (10), so as to be mirror images in relation to the transversal central plane of the lifting frame (7), that clamping or alignment strips (31, 32) are fastened to the opposing chains (27, 28) at right angles to the conveying direction, and that the chains (27, 28) are provided in such a manner with drives that they traverse the alignment strips in opposing directions.
 3. Device, as claimed in claim 2 , characterized in that the shafts (24, 25) of the inside chain wheels (26) are coupled together by means of gearwheels (29).
 4. Device, as claimed in claim 3 , characterized in that a pressure medium piston cylinder unit (36) acts as the drive on a chain (28).
 5. Device, as claimed in any one of the claims 1 to 4 , characterized in that on both sides of the lifting frame (7) are mounted rollers (41) or chain wheels around axles, pointing in the conveying direction, and that two continuous traction means (42) or chains run over said chain wheels, and that the sliders (44, 46) or clamping strips, which run parallel to each other over holders and which can be moved in opposite directions through a synchronous drive of the chains, are fastened to the upper strands and the lower strands of the chains or traction means.
 6. Device, as claimed in claim 5 , characterized in that the sliders (44, 46) are guided by means of guide elements, for example sleeves (47, 48), on a traverse (20), which runs at right angles to said sleeves.
 7. Device, as claimed in claim 5 or 6 , characterized in that to drive the chains or traction means there is a pressure medium piston cylinder unit (51), whose piston rod (50) is fastened to a slider (46) and whose cylinder is fastened to the lifting frame (7).
 8. Device, as claimed in any one of the preceding claims, characterized in that the pressure medium piston cylinder units are pneumatic cylinders.
 9. Device, as claimed in any one of the claims 1 to 8 , characterized in that the lifting frame (7) is provided with driven rollers (8). 